Compensating device for gas actuated firearms

Abstract

An autoloading shotgun having a receiver, a barrel projecting from the receiver, a magazine tube supported on the receiver in parallel relation to the barrel, a generally cylindrical gas cylinder mounted in fixed position relative to the barrel and coaxially surrounding relation to an associated portion of the magazine tube, and in an annular piston received within the gas chamber and coaxially surrounding an associated portion of the magazine tube and supported for movement along the magazine tube and toward and away from the receiver. The gas cylinder, magazine tube and piston cooperate to define an annular a gas chamber in communication with the shotgun bore. An obturation ring coaxially surrounding the magazine tube forward of the gas cylinder is biased into engagement with an annular seating surface on the forward end of the gas cylinder to provide a closure for gas ports communicating with the gas chamber and opening through the seating surface. The obturation ring moves along the magazine tube and away from the gas cylinder to vent gases of explosion from the gas cylinder when the pressure within the gas cylinder exceeds a predetermined magnitude.

I claim: 
     
       1. In a firearm having a receiver, a barrel supported on and projecting forwardly of the receiver and including a bore, a breech bolt supported within the receiver for movement therein between battery and retired positions, a magazine tube supported on and projecting forwardly of the receiver in axially parallel relation to the barrel, a generally cylindrical gas cylinder mounted in fixed position relative to the barrel and coaxially surrounding an associated portion of the magazine tube in axially spaced relation to the receiver, an annular piston received within the gas cylinder and coaxially surrounding an associated portion of the magazine tube, the piston being supported on said magazine tube for movement therealong and generally toward and away from the receiver, action bar means for moving the breech bolt in response to movement of the piston relative to the gas cylinder, the cylinder cooperating with the magazine tube and the piston to define an annular gas chamber, means defining a bleed port communicating with the bore and with the gas chamber forward of the piston for venting gases of explosion from the bore into the gas chamber, and compensating means for limiting pressure developed within the gas chamber, the improvement wherein said compensating means comprises a generally radially disposed and forwardly facing first annular seating surface on said gas cylinder, at least one gas vent port defined by said gas cylinder communicating with said gas chamber and opening through said first annular seating surface, an obturation ring supported in coaxial encircling relation to an associated portion of said magazine tube forward of said gas cylinder and having a generally radially disposed and rearwardly facing second annular seating surface for seating engagement with said first annular seating surface, and means for biasing said obturation ring toward said gas cylinder to maintain second annular seating surface in seating engagement with said first annular seating surface and in closing relation to said one gas vent port when the magnitude of pressure within said gas cylinder is lower than a predetermined magnitude, said obturation ring being movable away from said gas cylinder and out of seating engagement in response to pressure within said chamber in excess of said predetermined magnitude to vent gases of explosion from said gas chamber through said one gas port and to the atmosphere. 
     
     
       2. In a firearm as set forth in claim 1 the further improvement wherein said compensating means comprises a plurality of gas vent ports opening through said first annular surface at equiangularly spaced locations about the axis of said gas cylinder. 
     
     
       3. In a firearm as set forth in claim 1 wherein said biasing means is further characterized as spring biasing means. 
     
     
       4. In a firearm as set forth in claim 3 the further improvement wherein said spring biasing means comprises a plurality of springs. 
     
     
       5. In a firearm having a receiver, a barrel supported on and projecting forwardly of the receiver and including a bore, a breech bolt supported within the receiver for movement therein between battery and retired positions, a magazine tube supported on and projecting forwardly of the receiver in axially parallel relation to the barrel, a generally cylindrical gas cylinder mounted in fixed position relative to the barrel and coaxially surrounding an associated portion of the magazine tube in axially spaced relation to the receiver, an annular piston received within said gas cylinder and coaxially surrounding an associated portion of the magazine tube, said piston being supported on the magazine tube for movement therealong and generally toward and away from the receiver, an action bar connected to the breech bolt and to the piston for moving the breech bolt in response to movement of the piston relative to the gas cylinder, the gas cylinder cooperating with the magazine tube and the piston to define an annular gas chamber coaxially surrounding an associated portion of the magazine tube, means defining a bleed port communicating with the bore and with the gas chamber forward of the piston for venting gases of explosion from the bore into the gas chamber, and compensating means for limiting pressure developed within the gas chamber, the improvement wherein said compensating means comprises a generally radially disposed and forwardly facing first annular seating surface on said gas cylinder, a plurality of gas vent ports defined by said gas cylinder in communication with said gas chamber and opening through said first annular seating surface at equiangularly spaced locations about the axis of said magazine tube, an obturation ring received on and coaxially surrounding an associated portion of said magazine tube forward of said gas cylinder and having a generally radially disposed and rearwardly facing second annular seating surface for seating engagement with said first annular seating surface to form a closure for said gas vent ports opening through said first annular seating surface, a plurality of studs threadably engaged with said gas cylinder and projecting forwardly from said first annular seating surface in equiangularly spaced relation about the axis of said magazine tube, said studs extending through said obturation ring and supporting said ring for sliding movement therealong generally toward and away from said first seating surface, a plurality of nuts equal in number to said guide rods, each of said nuts being received on the free end of an associated one of said guide rods, and a plurality of compression springs equal in number to said guide rods, each of said springs being received upon an associated one of said guide rods and acting between an associated nut and said obturation ring, said springs biasing said obturation ring toward said gas cylinder and maintaining said second annular seating surface in engagement with said first annular seating surface and in closing relation with said gas vent ports opening through said first annular seating surface when the magnitude of pressure within said gas cylinder is lower than a predetermined magnitude, said obturation ring being movable away from said gas cylinder and out of seating engagement in response to pressure within said chamber in excess of said predetermined magnitude to vent gases of explosion from said gas chamber through said gas vent ports and to the atmosphere. 
     
     
       6. In a firearm having a receiver, a barrel supported on and projecting forwardly of the receiver and including a bore, a breech bolt supported within the receiver for movement therein between battery and retired positions, a magazine tube supported on and projecting forwardly of the receiver in axially parallel relation to the barrel, a generally cylindrical gas cylinder mounted in fixed position relative to the barrel and coaxially surrounding an associated portion of the magazine tube in axially spaced relation to the receiver, an annular piston received within the gas cylinder and coaxially surrounding an associated portion of the magazine tube, the piston being supported on said magazine tube for movement therealong and generally toward and away from the receiver, action bar means for moving the breech bolt in response to movement of the piston relative to the gas cylinder, the gas cylinder cooperating with the magazine tube and the piston to define an annular gas chamber, means defining a bleed port communicating with the bore and with the gas chamber forward of the piston for venting gases of explosion from the bore into the gas chamber, and compensating means for limiting pressure developed by gases of explosion within the gas chamber, the improvement wherein said compensating means comprises a generally radially disposed and forwardly facing first annular seating surface on said gas cylinder, at least one gas vent port defined by said gas cylinder communicating with said gas chamber and opening through said first annular seating surface, a plurality of guide members mounted in fixed position on and projecting forwardly from said gas cylinder in axially parallel relation to the axis of said magazine tube, an obturation ring supported on said guide members in coaxial encircling relation to an associated portion of said magazine tube forward of said gas cylinder and having a generally radially disposed and rearwardly facing second annular seating surface for seating engagement with said first annular seating surface, a stabalizing ring coaxially encircling said magazine tube and received on forward end portions of said guide members, and a plurality of springs equal in number to said guide members, each of said springs received on an associated one of said guide members, said springs acting between said stabalizing ring and said obturation ring and biasing said obturation ring toward said gas cylinder to maintain second annular seating surface in seating engagement with said first annular seating surface and in closing relation to said one gas vent port when the pressure within said gas cylinder is lower than a predetermined magnitude, said obturation ring being movable away from said gas cylinder and out of seating engagement with said cylinder in response to pressure within said chamber in excess of said predetermined magnitude to vent gases of explosion from said gas chamber through said one gas port and to the atmosphere. 
     
     
       7. In a firearm as set forth in claim 6 the further improvement comprising a plurality of nuts equal in number to said rods, each of said nuts being threadably engaged with the forward end portion of an associated rod forward of said stabalizing ring. 
     
     
       8. In a firearm having a receiver, a barrel supported on and projecting forwardly of the receiver and including a bore, a breech bolt supported within the receiver for movement therein between battery and retired positions, a magazine tube supported on and projecting forwardly of the receiver in axially parallel relation to the barrel, a generally cylindrical gas cylinder mounted in fixed position relative to the barrel and coaxially surrounding an associated portion of the magazine tube in axially spaced relation to the receiver, an annular piston received within the gas cylinder and coaxially surrounding an associated portion of the magazine tube, the piston being supported on said magazine tube for movement therealong and generally toward and away from the receiver, action bar means for moving the breech bolt in response to movement of the piston relative to the gas cylinder, the cylinder cooperating with the magazine tube and the piston to define and annular gas chamber, means defining a bleed port communicating with the bore and with the gas chamber forward of the piston for venting gases of explosion from the bore into the gas chamber, and compensating means for limiting pressure developed within the gas chamber, the improvement wherein said compensating means comprises a generally radially disposed and forwardly facing first annular seating surface on said gas cylinder, at least one gas vent port defined by said gas cylinder communicating with said gas chamber and opening through said first annular seating surface, an obturation ring supported in coaxial encircling relation to an associated portion of said magazine tube forward of said gas cylinder and having a generally radially disposed and rearward facing second annular seating surface for seating engagement with said first annular seating surface, a plurality of guide members mounted in fixed position on and projecting forwardly from said gas cylinder in axially parallel relation to the axis of the magazine tube, and means for biasing said obturation ring toward said gas cylinder to maintain second annular seating surface in seating engagement with said first annular seating surface and in closing relation to said one gas vent port when the magnitude of pressure within said gas cylinder is lower than a predetermined magnitude and including a plurality of springs equal in number to said guide members, each of said springs received on an associated one of said guide members and acting upon said obturation ring, said obturation ring being movable away form said gas cylinder and out of seating engagement with said first annular seating surface in response to pressure within said chamber in excess of said predetermined magnitude to vent gases of explosion from said gas chamber through said one gas port and to the atmosphere. 
     
     
       9. In a firearm as set forth in claim 8 the further improvement wherein each of said guide members comprises a stud threadably engaged with said gas cylinder and a cap nut threadably engaged with the free end of said stud and said associated spring is disposed between said cap nut and said obturation ring. 
     
     
       10. In a firearm as set forth in claim 8 including the further improvement wherein said compensating means includes means for adjusting said predetermined pressure. 
     
     
       11. In a firearm as set forth in claim 10 the further improvement wherein said adjusting means comprises threaded fasteners.